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Magnetic Recording Media with Mechanical Texture formed by a Mold

IP.com Disclosure Number: IPCOM000015517D
Original Publication Date: 2002-Apr-15
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Abstract

This paper discloses a magnetic recording disk made with a molded substrate embossed with circumferential texture. Such texture is used in the hard disk drive industry to help align the easy axis of the magnetic grains in the circumferential direction. This is known to improve the magnetic performance of the media. Currently, circumferential texture is imposed on metal hard disks with an abrasive mechanical process. However, magnetic recording disks made of plastic and most disks made of glass do not have such circumferential texture. Disclosed is the making of a textured disk, with plastic or another material, by embedding the desired texture in the mold.

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Magnetic Recording Media with Mechanical Texture formed by a Mold

    This paper discloses a magnetic recording disk made with a molded substrate embossed with circumferential texture. Such texture is used in the hard disk drive industry to help align the easy axis of the magnetic grains in the circumferential direction. This is known to improve the magnetic performance of the media. Currently, circumferential texture is imposed on metal hard disks with an abrasive mechanical process. However, magnetic recording disks made of plastic and most disks made of glass do not have such circumferential texture. Disclosed is the making of a textured disk, with plastic or another material, by embedding the desired texture in the mold.

Aluminum disks are routinely polished to add mechanical texture in the circumferential direction. Mechanically-polished glass and nickel-phosphorous-coated glass substrates are under development. In contrast, plastic disks are currently isotropically smooth. Molded plastic disks are used for magnetic recording and for magneto-optical recording.

    Plastic injection molded disks have a significant cost advantage over the traditional textured aluminum disks and isotropic glass disks used in hard disk drives. Putting the textured pattern into the mold eliminates costly polishing steps on every disk. Because the disk's texture comes from the mold, there will be less variation in surface texture between different disks. The texture quality may improve because the substantial effort needed to make good texture must be done only on the mold, instead of on every disk, as is currently done on aluminum disks. Figure 1 is a schematic cross-section (not to scale) o...